Papers by Philip Greenwood
Geographica helvetica
Raindrop impact and subsequent aggregate breakdown can potentially change the movement behaviour ... more Raindrop impact and subsequent aggregate breakdown can potentially change the movement behaviour of soil fractions and thus alter their transport distances when compared against non-impacted aggregates. In a given water layer, the transport distances of eroded soil fractions, and thus that of the associated substances across landscapes, such as soil organic carbon (SOC) and phosphorous, are determined by the settling velocities of the eroded soil fractions. However, using mineral size distribution to represent the settling velocities of soil fractions, as often applied in current erosion models, would ignore the potential influence of aggregation on the settling behaviour of soil fractions. The destructive effects of raindrops impacting onto aggregates are also often neglected in current soil erosion models. Therefore, the objective of this study is to develop a proxy method to effectively simulate aggregate breakdown under raindrop impact, and further identify the settling velocity...
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Journal of Soils and Sediments, Dec 20, 2013
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Die Erde Zeitschrift Der Gesellschaft Fur Erdkunde Zu Berlin, Jul 13, 2013
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Hydrology, 2015
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Agriculture, Ecosystems & Environment, 2016
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Geographica helvetica
Raindrop impact and subsequent aggregate breakdown can potentially change the movement behaviour ... more Raindrop impact and subsequent aggregate breakdown can potentially change the movement behaviour of soil fractions and thus alter their transport distances when compared against non-impacted aggregates. In a given water layer, the transport distances of eroded soil fractions, and thus that of the associated substances across landscapes, such as soil organic carbon (SOC) and phosphorous, are determined by the settling velocities of the eroded soil fractions. However, using mineral size distribution to represent the settling velocities of soil fractions, as often applied in current erosion models, would ignore the potential influence of aggregation on the settling behaviour of soil fractions. The destructive effects of raindrops impacting onto aggregates are also often neglected in current soil erosion models. Therefore, the objective of this study is to develop a proxy method to effectively simulate aggregate breakdown under raindrop impact, and further identify the settling velocity...
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The environmental characteristics of many artificial gamma-emitting radionuclides provide a numbe... more The environmental characteristics of many artificial gamma-emitting radionuclides provide a number of distinct advantages over other forms of fine-sediment tracer that are readily exploitable when undertaking erosion investigations. This makes them particularly effective for accurately measuring the movement of small quantities of fine-sediment, especially in low-energy environments where soil movement is commensurately small, or for measuring erosion rates over short (i.e. event-based) timescales. The major advantages and disadvantages associated with their use as tracers are outlined and briefly discussed. Three examples of tracing applications using caesium-134 (134 Cs) and cobalt-60 (60 Co) are summarised in order to highlight their versatility and demonstrate the diverse ways in which they can be used in field-and laboratory-based investigations.
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Earth Surface Processes and Landforms, 2014
ABSTRACT In a review of the role of plants in river systems, Gurnell (2014) explains how living r... more ABSTRACT In a review of the role of plants in river systems, Gurnell (2014) explains how living riparian vegetation can exert physical controls that enable it to modify and manipulate many fluvial processes. Those traits, in combination with their tendency to speed up the recovery of river systems between extreme flow events through their stabilising influence, imply that plants may act as ‘river system engineers’. In this sense, vegetation may be important in attenuating erosion during high flow and stabilising river features both during and after extreme flow conditions. This article is protected by copyright. All rights reserved.
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Journal of Soils and Sediments, 2014
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Earth Surface Processes and Landforms, 2014
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The influence and effect of biochar on soil properties has been intensively investigated, particu... more The influence and effect of biochar on soil properties has been intensively investigated, particularly in the context of its potential to sequester carbon and mitigate the effects of anthropogenic climate change. One major question that remains unanswered concerns the erodibility and fate of biochar in the landscape. Since biochar has a lower bulk-density than soil, preferential erosion of biochar is most likely. However, until now, almost no actual data on the enrichment of biochar in in the eroded sediment or the net loss from fields exist. This important gap of knowledge could have profound economic implications for farmers committed to its use, since a high net annual loss of biochar by erosion could exceed any net annual economic gain. Most importantly, any positive gain for the environment largely depends on the amount of biochar that remains within the upper soil matrix. The overall objective of this study was to explicitly investigate the erodibility of biochar, if erosion e...
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This communication describes the main components of a laboratory facility for use in investigatio... more This communication describes the main components of a laboratory facility for use in investigations where erosion results from rain-impacted flow. The equipment consists of a rainfall simulator over a flume containing an erodible surface, and was developed to enable key properties associated with surface runoff and shallow-flow characteristics to be controlled and manipulated so that their respective influence on mobilisation mechanisms can be isolated and measured. This paper outlines the main components of the experimental erosion measurement facility. Key properties associated with the control and measurement of precipitation, runoff and erosion conditions during simulated rainfall events are described and some preliminary results are presented and briefly discussed. The findings illustrate the ability of the equipment to control conditions over multiple rainfall simulations and the need for operators to become fully conversant with the equipment. It is envisaged that data produc...
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In recent years, the influence and effect of biochar on soil properties has been intensively inve... more In recent years, the influence and effect of biochar on soil properties has been intensively investigated, particularly in the context of its potential to mitigate the effects of anthropogenic climate change by acting as a net carbon sink. However, a lack of evidence to support the influence and positive effects of biochar on physical and chemical processes in edaphic ecosystems represents a major limitation in its viability as a ‘soft’ geo-engineering option to contribute to ameliorating anthropogenic climate change. One major question that remains unanswered concerns the mobilization, fate and erodibility of biochar in the landscape. Since biochar has a lower bulk-density than soil, its susceptibility to erosion is expected. This lack of information is important and could have profound economic implications for farmers committed to its use, since a high net annual loss of biochar by erosion could exceed any net annual economic gain in terms of increased TOC stocks, as well as any ...
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Developments in Earth Surface Processes, 2014
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Papers by Philip Greenwood